1. Field of the Invention
The present invention relates to lens barrels and, more particularly, to a lens barrel in which it has a data projecting mechanism within a camera body, and photographing information is projected onto a film surface through a portion of the lens barrel.
2. Related Art And Prior Art Statement
A camera has been known in which desired photographing information data such as a photographing date and the like can be projected onto a film surface. Almost all of the conventional cameras each having a data projecting mechanism is arranged such that a rear lid or closure of the camera is provided therein with the data projecting mechanism, and data can be projected from the side of a rear surface of an emulsion of the film.
However, if the data projecting mechanism is arranged within the rear closure of the camera to project the data from the side of the rear surface of the film in this manner, there are the following problems and the like:
1) Thickness of the rear closure of the camera increases so that the camera is large-sized. Thus, portability and holding ability are reduced. PA1 2) Because of giving and receiving of an electric signal between a data projecting unit arranged within the rear closure of the camera and a CPU arranged within the camera body, an electric connection between the data projecting unit and the CPU is required. For this reason, a structure or construction is complicated.
Accordingly, in order to solve the above-discussed problem, it is preferable to take an arrangement in which the data projecting mechanism is arranged adjacent to the camera body, and data can be projected from the side of a front surface of the film. If the camera is arranged in this manner, however, in the camera body having no space, the data projecting mechanism is arranged above a portion within the camera body. Then, in a case of a drum-sinking camera or the like, rear portions of respective stationary or fixed tube and a rotary drive tube in the lens barrel are necessarily interposed between the data projecting mechanism and the film, to interrupt a ray of light for date projection. Accordingly, in order to lead the ray of light for date projection onto the film surface, bores must be provided which causes the ray of light for date projection to pass, at rear portions of the respective fixed tube and rotary drive tube.
However, if the bores are provided, even in a non-photographing condition such as an unused condition of the camera, the bores provided in the rear portions of the respective fixed tube and rotary drive tube are always under a condition being opened. Accordingly, although the bores are anyhow covered by the data projecting mechanism, there are no other interrupting objects or items. Thus, there is a fear that, under a nonuse condition and a conservation condition for a long period of time, an outward light approaches so that light leakage occurs, and the film is exposed.